scholarly journals Role of actin polymerization in bending of the early heart tube

2005 ◽  
Vol 233 (4) ◽  
pp. 1272-1286 ◽  
Author(s):  
Kimberly S. Latacha ◽  
Mathieu C. Rémond ◽  
Ashok Ramasubramanian ◽  
Amy Y. Chen ◽  
Elliot L. Elson ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Heart Tube

Mechanical Forces Involved in Cardiac C-Looping

2004 ◽  
Author(s):  
Larry A. Taber ◽  
Dmitry A. Voronov ◽  
Mathieu C. Re´mond ◽  
Kimberly S. Latacha ◽  
Patrick W. Alford
Keyword(s):  
Actin Polymerization ◽  
Mechanical Forces ◽  
Embryonic Chick ◽  
Heart Tube ◽  
Curved Tube ◽  
Shaped Tube ◽  
Biomechanical Forces ◽  
The Right ◽  
External Loads

Cardiac looping is a vital morphogenetic process that transforms the initially straight heart tube into a curved tube normally directed toward the right side of the embryo. We examined the role of biomechanical forces during the initial stages of looping, when the heart bends and rotates into a c-shaped tube (c-looping). C-looping consists of two primary deformation components: ventral bending and dextral (rightward) rotation (torsion). Embryonic chick hearts were subjected to mechanical and chemical perturbations, and the experiments were simulated using a computational model. The results suggest that bending is driven primarily by actin polymerization within the heart tube, while rotation is driven by external loads due to the splanchnopleure and omphalomesenteric veins. The results of this study may help investigators searching for the link between gene expression and the mechanical processes that drive looping.

Role of Mechanical Feedback in Restoration of Normal Cardiac C-Looping Following Perturbed Loading

2007 ◽  
Author(s):  
Ashok Ramasubramanian ◽  
Nandan L. Nerurkar ◽  
Kate H. Achtien ◽  
Larry A. Taber
Keyword(s):  
Actin Polymerization ◽  
Ventral Side ◽  
The Body ◽  
Developmental Phase ◽  
Heart Tube ◽  
Shaped Tube ◽  
Dorsal Mesocardium ◽  
External Forces ◽  
The Right

Cardiac c-looping is an important developmental phase, as the initially straight heart tube (HT) is transformed into a c-shaped tube. Looping consists of two distinct processes: ventral bending, which is likely driven by actin polymerization, and dextral torsion, which is likely due to external forces. These forces are applied by a membrane enveloping the ventral side of the heart, the splanchnopleure (SPL, Fig. 2A) and a pair of atria that flank the caudal end of the heart tube (HT, Fig 1A). In particular, the atria provide the initial push, biasing the HT towards the right while the SPL applies a ventrally directed force, which causes the HT to rotate using the dorsal mesocardium (DM, Fig. 2A) as a pivot (the DM attaches the dorsal length of the heart to the body of the embryo).

Current Study of RhoA and Associated Signaling Pathways in Gastric Cancer

2020 ◽  
Vol 15 (7) ◽  
pp. 607-613 ◽  
Author(s):  
Haiping Liu ◽  
Yiqian Liu ◽  
Xiaochuan Zhang ◽  
Xiaodong Wang
Keyword(s):  
Gastric Cancer ◽  
Survival Rate ◽  
Signaling Pathways ◽  
Tumor Cells ◽  
Actin Polymerization ◽  
Cell Transformation ◽  
Cell Movement ◽  
Invasion And Metastasis ◽  
Common Cancer

Gastric cancer (GC) is the fourth-most common cancer in the world, with an estimated 1.034 million new cases in 2015, and the third-highest cause of cancer deaths, estimated at 785,558, in 2014. Early diagnosis and treatment greatly affect the survival rate in patients with GC: the 5‐year survival rate of early GC reaches 90%‐95%, while the mortality rate significantly increases if GC develops to the late stage. Recently, studies for the role of RhoA in the diseases have become a hot topic, especially in the development of tumors. A study found that RhoA can regulate actin polymerization, cell adhesion, motor-myosin, cell transformation, and the ability to participate in the activities of cell movement, proliferation, migration, which are closely related to the invasion and metastasis of tumor cells. However, the specific role of RhoA in tumor cells remains to be studied. Therefore, our current study aimed to briefly review the role of RhoA in GC, especially for its associated signaling pathways involved in the GC progression.

scholarly journals The activity status of cofilin is directly related to invasion, intravasation, and metastasis of mammary tumors

2006 ◽  
Vol 173 (3) ◽  
pp. 395-404 ◽  
Author(s):  
Weigang Wang ◽  
Ghassan Mouneimne ◽  
Mazen Sidani ◽  
Jeffrey Wyckoff ◽  
Xiaoming Chen ◽  
...  
Keyword(s):  
Cell Motility ◽  
Cell Invasion ◽  
Actin Polymerization ◽  
Cancer Cell Invasion ◽  
Invasion And Metastasis ◽  
Over Expression ◽  
Cell Biol ◽  
Tumor Cell Motility ◽  
New Strategies

Understanding the mechanisms controlling cancer cell invasion and metastasis constitutes a fundamental step in setting new strategies for diagnosis, prognosis, and therapy of metastatic cancers. LIM kinase1 (LIMK1) is a member of a novel class of serine–threonine protein kinases. Cofilin, a LIMK1 substrate, is essential for the regulation of actin polymerization and depolymerization during cell migration. Previous studies have made opposite conclusions as to the role of LIMK1 in tumor cell motility and metastasis, claiming either an increase or decrease in cell motility and metastasis as a result of LIMK1 over expression (Zebda, N., O. Bernard, M. Bailly, S. Welti, D.S. Lawrence, and J.S. Condeelis. 2000. J. Cell Biol. 151:1119–1128; Davila, M., A.R. Frost, W.E. Grizzle, and R. Chakrabarti. 2003. J. Biol. Chem. 278:36868–36875; Yoshioka, K., V. Foletta, O. Bernard, and K. Itoh. 2003. Proc. Natl. Acad. Sci. USA. 100:7247–7252; Nishita, M., C. Tomizawa, M. Yamamoto, Y. Horita, K. Ohashi, and K. Mizuno. 2005. J. Cell Biol. 171:349–359). We resolve this paradox by showing that the effects of LIMK1 expression on migration, intravasation, and metastasis of cancer cells can be most simply explained by its regulation of the output of the cofilin pathway. LIMK1-mediated decreases or increases in the activity of the cofilin pathway are shown to cause proportional decreases or increases in motility, intravasation, and metastasis of tumor cells.

scholarly journals Rho-mDia1 pathway is required for adhesion, migration, and T-cell stimulation in dendritic cells

Blood ◽  
2010 ◽  
Vol 116 (26) ◽  
pp. 5875-5884 ◽  
Author(s):  
Hideaki Tanizaki ◽  
Gyohei Egawa ◽  
Kayo Inaba ◽  
Tetsuya Honda ◽  
Saeko Nakajima ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Dendritic Cells ◽  
T Cell ◽  
Immune Responses ◽  
Lymph Nodes ◽  
Actin Polymerization ◽  
Cell Stimulation ◽  
T Cell Stimulation ◽  
Acquired Immune Responses

Abstract Dendritic cells (DCs) are essential for the initiation of acquired immune responses through antigen acquisition, migration, maturation, and T-cell stimulation. One of the critical mechanisms in this response is the process actin nucleation and polymerization, which is mediated by several groups of proteins, including mammalian Diaphanous-related formins (mDia). However, the role of mDia in DCs remains unknown. Herein, we examined the role of mDia1 (one of the isoforms of mDia) in DCs. Although the proliferation and maturation of bone marrow-derived DCs were comparable between control C57BL/6 and mDia1-deficient (mDia1−/−) mice, adhesion and spreading to cellular matrix were impaired in mDia1−/− bone marrow–derived DCs. In addition, fluorescein isothiocyanate-induced cutaneous DC migration to draining lymph nodes in vivo and invasive migration and directional migration to CCL21 in vitro were suppressed in mDia1−/− DCs. Moreover, sustained T-cell interaction and T-cell stimulation in lymph nodes were impaired by mDia1 deficiency. Consistent with this, the DC-dependent delayed hypersensitivity response was attenuated by mDia1-deficient DCs. These results suggest that actin polymerization, which is mediated by mDia1, is essential for several aspects of DC-initiated acquired immune responses.

scholarly journals Myosin-II activity generates a dynamic steady state with continuous actin turnover in a minimal actin cortex

2018 ◽  
Author(s):  
Sonal ◽  
Kristina A. Ganzinger ◽  
Sven K. Vogel ◽  
Jonas Mücksch ◽  
Philipp Blumhardt ◽  
...  
Keyword(s):  
Steady State ◽  
Actin Polymerization ◽  
Myosin Ii ◽  
Fine Tuning ◽  
Cellular Functions ◽  
Actin Cortex ◽  
Actin Turnover ◽  
Cytoskeletal Dynamics

ABSTRACTDynamic reorganization of the actomyosin cytoskeleton allows a fine-tuning of cell shape that is vital to many cellular functions. It is well established that myosin-II motors generate the forces required for remodeling the cell surface by imparting contractility to actin networks. An additional, less understood, role of myosin-II in cytoskeletal dynamics is believed to be in the regulation of actin turnover; it has been proposed that myosin activity increases actin turnover in various cellular contexts, presumably by contributing to disassembly. In vitro reconstitution of actomyosin networks has confirmed the role of myosin in actin network disassembly, but factors such as diffusional constraints and the use of stabilized filaments have thus far limited the observation of myosin-assisted actin turnover in these networks. Here, we present the reconstitution of a minimal dynamic actin cortex where actin polymerization is catalyzed on the membrane in the presence of myosin-II activity. We demonstrate that myosin activity leads to disassembly and redistribution in this simplified cortex. Consequently, a new dynamic steady state emerges in which actin filaments undergo constant turnover. Our findings suggest a multi-faceted role of myosin-II in fast remodeling of the eukaryotic actin cortex.

scholarly journals Chemo-mechanical Diffusion Waves Orchestrate Collective Dynamics of Immune Cell Podosomes

2021 ◽  
Author(s):  
Ze Gong ◽  
Koen van den Dries ◽  
Alessandra Cambi ◽  
Vivek Shenoy
Keyword(s):  
Actin Polymerization ◽  
Immune Cell ◽  
Wave Dynamics ◽  
Diffusion Waves ◽  
Mechanical Diffusion ◽  
Mechanical Waves ◽  
The Individual ◽  
The Impact ◽  
Cell Mechanosensing

Immune cells, such as macrophages and dendritic cells, can utilize podosomes, actin-rich protrusions, to generate forces, migrate, and patrol for foreign antigens. In these cells, individual podosomes exhibit periodic protrusion and retraction cycles (vertical oscillations) to probe their microenvironment, while multiple podosomes arranged in clusters demonstrate coordinated wave-like spatiotemporal dynamics. However, the mechanisms governing both the individual vertical oscillations and the coordinated oscillation waves in clusters remain unclear. By integrating actin polymerization, myosin contractility, actin diffusion, and mechanosensitive signaling, we develop a chemo-mechanical model for both the oscillatory growth of individual podosomes and wave-like dynamics in clusters. Our model reveals that podosomes show oscillatory growth when the actin polymerization-associated protrusion and the signaling-associated myosin contraction occur at similar rates, while the diffusion of actin monomers within the cluster drives mesoscale coordination of individual podosome oscillations in an apparent wave-like fashion. Our model predicts the influence of different pharmacological treatments targeting myosin activity, actin polymerization, and mechanosensitive pathways, as well as the impact of the microenvironment stiffness on the wavelengths, frequencies, and speeds of the chemo-mechanical waves. Overall, our integrated theoretical and experimental approach reveals how collective wave dynamics arise due to the coupling between chemo-mechanical signaling and actin diffusion, shedding light on the role of podosomes in immune cell mechanosensing within the context of wound healing and cancer immunotherapy.

scholarly journals Role of PI3-Kinase and PI4-Kinase in Actin Polymerization During Bovine Sperm Capacitation1

2007 ◽  
Vol 77 (2) ◽  
pp. 263-273 ◽  
Author(s):  
Nir Etkovitz ◽  
Sara Rubinstein ◽  
Limor Daniel ◽  
Haim Breitbart
Keyword(s):  
Actin Polymerization ◽  
Pi3 Kinase ◽  
Bovine Sperm

Actin reorganization and proplatelet formation in murine megakaryocytes: the role of protein kinase Cα

Blood ◽  
2001 ◽  
Vol 97 (1) ◽  
pp. 154-161 ◽  
Author(s):  
Ponlapat Rojnuckarin ◽  
Kenneth Kaushansky
Keyword(s):  
Protein Kinase ◽  
Actin Polymerization ◽  
Map Kinases ◽  
Molecular Mechanisms ◽  
Marrow Cell ◽  
Actin Dynamics ◽  
Actin Reorganization ◽  
Murine Bone Marrow ◽  
Proplatelet Formation

Abstract With the recent cloning and characterization of thrombopoietin, appreciation of the molecular events surrounding megakaryocyte (MK) development is growing. However, the final stages of platelet formation are less well understood. Platelet production occurs after the formation of MK proplatelet processes. In a study to explore the molecular mechanisms underlying this process, mature MKs isolated from suspension murine bone marrow cell cultures were induced to form proplatelets by exposure to plasma, and the role of various cell-signaling pathways was assessed. The results showed that (1) bis-indolylmaleimide I, which blocks protein kinase C (PKC) activation; (2) down-modulation of conventional or novel classes of PKC by phorbol myristate acetate; and (3) ribozymes specific for PKCα each inhibited proplatelet formation. Inhibition of several MAP kinases, PI3 kinase, or protein kinase A failed to affect MK proplatelet formation. To gain further insights into the function of PKCα in proplatelet formation, its subcellular localization was investigated. In cultures containing active proplatelet formation, cytoplasmic polymerized actin was highly aggregated, its subcellular distribution was reorganized, and PKCα colocalized with the cellular actin aggregates. A number of MK manipulations, including blockade of integrin signaling with a disintegrin or inhibition of actin polymerization with cytochalasin D, interrupted actin reorganization, PKC relocalization, and proplatelet formation. These findings suggest an important role for PKCα in proplatelet development and suggest that it acts by altering actin dynamics in proplatelet-forming MKs. Identification of the upstream and downstream pathways involved in proplatelet formation should provide greater insights into thrombopoiesis, potentially allowing pharmacologic manipulation of the process.

scholarly journals Interaction of Enteropathogenic and Shiga Toxin-Producing Escherichia coli and Porcine Intestinal Mucosa: Role of Intimin and Tir in Adherence

2005 ◽  
Vol 73 (9) ◽  
pp. 6005-6016 ◽  
Author(s):  
Francis Girard ◽  
Isabelle Batisson ◽  
Gad M. Frankel ◽  
Josée Harel ◽  
John M. Fairbrother
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Actin Polymerization ◽  
Animal Species ◽  
Ex Vivo ◽  
Epec Strain ◽  
E Coli ◽  
In Vitro Organ Culture

ABSTRACT The ileal in vitro organ culture (IVOC) model using tissues originating from colostrum-deprived newborn piglets has proven to be an effective way to study the attaching and effacing (A/E) phenotype of porcine enteropathogenic Escherichia coli (EPEC) ex vivo. The aim of this study was to investigate the role of intimin subtype and Tir in the adherence of EPEC and Shiga-toxin-producing E. coli (STEC), isolated from different animal species, to porcine intestinal IVOC. Moreover, the role of intimin in Tir-independent adherence of the human EPEC strain E2348/69 was investigated using intimin and Tir-deficient derivatives. Our results demonstrated that A/E E. coli strains (AEEC) from various animal species and humans induce the A/E phenotype in porcine ileal IVOC and that intimin subtype influences intestinal adherence and tropism of AEEC strains. We also showed that a tir mutant of EPEC strain E2348/69 demonstrates close adherence to the epithelial cells of porcine ileal IVOC segments, with microvillous effacement but with no evidence of actin polymerization or pedestal formation, and that intimin seems to be involved in this phenotype. Overall, this study provides further evidence for the existence of one or more host-cell-encoded intimin receptor(s) in the pig gut.

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